Process of forming jigs or fixtures.



B. M. WALPOLE. PROCESS OF FORMING .IIGS 0R FIXTURES.

APPLICATION FILED on. 24, 1914.

1,171,818. Patented Feb. 15, 71916.

2 SHEETS-SHEET I.

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B. M. WALPOLE.

PROCESS OF FORMING JIGS 0R FIXTURES.

APPLICATION FILED OCT. 24, 1914.

1,171,818. Patented Feb.15,'1916.

2 SHEETS-SHEET 2.

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nNirED T AT NT f BENJAMIN M. wALroLE, or rnovrnnncnnriohi: ISLAND, Assie'iioit'ro BuILDERs IRON FOUNDRY, or ritovinnnoii, s rens ISLAND, A CQRPGRATION or :nrionn ISLAND.

y rnocnss or romaine 'JIGS on rix'ruzans.

To all whomit'mtiy concern: Q Be it known that I, BENJAMIN M. WAL- PoLn, a citizen. of the United States,and resident of Providence, in the county of. Providence and State of Rhode Island, have This invention relates to animp'roved method or process of forming a jig or fixture ,to operate in connection with amagnetic chuck, and the invention has for its object to facilitate the construction of such a j g having a holding surface that conforms to the shape or contour of that surface of the work to be engaged by it. The usual practice of forming such "a jig for receiving work having an irregular or uneven surface, or a surface having one -or more pro turberances on the side opposite to that to be finishethisto provide a block of -cast iron having slots through it, in which are loosely placed the extension pole pieces of soft iron spaced to register with .the pole pieces in the chuck, these pieces are then fixed in position in these slots by calking or "forcing about. them some non-magnetic material, the upper surface of this'bl'ock is then cut out with a profile machine, milling tool or other mechanical device to form a holding surface conforming in contour to the uneven surface ofthat portion of the work to be held. This method as is well understood by those skilled in the art, isa long, tedious'and eX-f pensive operation. To obviate this expensive process and produce jig or fixture having a holding surface of the desired contour, at

the minimum expense, I use the work as a 7 pattern and place the extensionpoles in a mold and temporarilyhold .them properly or'other quick hardening non-magnetic material about these pieces, permanently fixing them in proper relationto eachaother i then surface thatportionof the jig adapted to engage the face of the chuck, andthe jig is' 'finished lat theflminimum expense with a. holding surface perfectly formed "to receive Specification of Letters Patent.

any number of pieces of workhaving the contour of the one used aslthe pattern.

With these and other objects in view, the

invention consists of certain novel features of construction, as will be more fully :de

scribed and particularly pointed out in the appended claims. i I In the accompanying{drawings: Figure 1.' is a side elevation showing my improved jigin section holding the work and mounted on the magnetic chuck inposition to be operated upon by the surfacing toolshQwn v Patented Fee-15, 19%.; I. Applicationfiled 00130116124, 1914. Serial No. 868,382.

above it. Fig. 2- is a perspective view of"' reduced size showingthe underside of a piece of work having a protuberance on its face to'be'v held. Fig. 3- is a perspecti e' view showing o ne of the gage plates employed for. positioning and temporarily supporting the magnetic pole pieces. Fig.

is a perspective view showing one form of the extension pole T316068. Fig. 5 1s a perspectiveview partially in section showing one form of'mold in which the work is used as'a patternand into which mold the pole pieces are positioned through gage plates and a' binder of non-magnetic ma-: terial deposited about the pole pieces to" reta'i-n them permanently with relation to'each 7 other, the outer face of this mold is subsequently surfaced whereby it is adapted to restupon the chuckas shown inFig. 1. Fig. 6+ is a perspective view of the finished mold with the 'work removed therefrom showing'the holding face having the-contour of that portion of the work to be held.

Fig. 7- is a perspective view showing the form and general arrangement of a gang of extension polepieces tied together by a singlemember. Fig. '8- shows-a sand mold in which this gang of pole" pieces may be formed and shapedto conform to "the engaging surfaceof the work by first forming a. pattern, then casting its shape in sand.

Fig. 9 is a perspective view partially in section ilhistrating another mold in which this gang of pole pieces are set-'withitheir ends resting upon the work after which a binder material-is formedaround the same topermanently fix the pieces, relative .to' each other, the supporting member at the.

top- I being 'subsequently broken. away. when :that ifaceof l the jig is surfaced or finished. 10 .is a section on' line 110-..10 of Fig.

9 showingasectional end view of the v 4 in which'is shown the work and one of the extension pole pieces conforming to the shape of the work. Fig. 11- is the finished jig having its holding; face shaped to conform to the contourof'thework.

Referring to the drawings 10 designates a portion of the base of a grinding machine onwhich the bed 11 is adapted to move 1ongitudmally on suitable ways and onthisbed is mounted a magnetic chuck 12 of any suitable form, the same being secured to the bed by bolts 13. p This magnetic chuck is shown as being provided "with a plurality of electromagnets 1 1- 'whose pole pieces extend through the upper plate 15 of the chuck. When it is desired to operate upon work which has a flat surface, the same is simply laid upon the faceof this chuck and the current turned on through the wires 16 which rigidly retain the work in position by mag netic force while it is beingacted upon by the surfacing tool 17. In the majority of 7 instances the surface of the work to be held is uneven, or irregular or has one or more protuberances extending from its under side which would prevent it from lying in proper position upon the surface of the ordinary magnetic chuck, therefore in order to sup-- port pieces of work of this character I have provided what is known as a jig or fixture for the purpose "of receiving and holdingpieces of work of this character andmy invention lies in an improved method of forming such jigs having extension pole ward. A pair of positioning or gage plates 2O constructed of brass or other suitable nonmagnetic material, is placed and spaced apart one above the other'in' this casing 18 and these gage plates are each provided with corresponding openings through them to receive and position the extension pole pieces 22 sothat their ends will register. with the poles of the magnets 14 in the chuck. It is only necessary now to drop theextension pole pieces through these openings and permit their lower ends to rest upon the surface of the work or pattern asillustrated in Fig. 5. In some cases the pole pieces 22 are made up of a series of fiat plates laid up side by side to better follow the contour of the work upon coming incontact there with.. Some of these extension pieces 22 will extend-farther: above-the mold than. others according to. the height of the pro-- .as molten Babbitt metal, plastic cement, or

tuberances against which they rest (see Fig.

5). In order to retain these extension pieces 1 in permanent :pcsitlonrelative to each: other" I now apply a suitable binding-maternal such other suitable material which will serve as an insulator andnot conduct the magnetlc lines of force. After this material has solidified for hardened I remove'the casing from the mold :and .surface ofithe outer face 23of the jig; l/Vhen finished this jigflor fixture appears as illustratedin Fig. 6 with the holding surface formed with the contour I ofthe engagingsurface of apiece of work-- and any number of pieces of the same shape maybe placed one after another into this to be operated upon bythesurfacing tool 1"? as illustrated in Fig. 1.

In somecases instead of temporarily supporting the extension pole pieces by the brass gage plate 20 I form these pole pieces in a gang as illustrated :inFig. 7 and tie them together by the member 24:. In form-. ing this gang of pole pieces I first place the work 19 on its face which is to be finished, .9 then Imake a wooden pattern and fit its 1- ends representing the pole pieces, to the back surface of the work. I then ram this pattern up in the usual way in molding sand and after withdrawing the pattern,

pour inmolten metal ofproper magnetic conductive qualities such as soft iron orthe like. This gang of pole-piecesthus formed is then removed from its mold 25 and is positioned in the shallower mold pieces will positively register with and en gage the magnetic polcs in the'chuck, and their opposite'ends will come into direct contact; with the surfaceofthe work what.-' ever its contour, all by a molding process and without the necessity of machining the workengaging surface of the jig.

Itis evident from the above that whether the pole pieces are formed separately and temporarily supported by gage. plates; or

whether these polepieces are cast in a gang andtemporarily supported by a tying ,mem-. her, the desired result'is-obtained and the cost of producing a 'jigorfixture of my im. proved construction having a holding; sun-- face of the contourof the Work is reduced to the very minimum.

I claim 2 1. An. improved. process, of constructingajig or fixture for an electric chuck which:

consists in positioning extension pole pieces in the mold, the work being used as a pattern and the ends of said pieces being brought into contact therewith while in the process of setting, and then depositing a binder of non-magnetic material about these pieces to permanently retain them in proper relation to each other.

2. An improved process of constructing a jig or fixture for an electric chuck which consists in placing extension pole pieces in a mold spaced apart to register with the pole pieces in the chuck, the work'being used as a pattern and the contacting ends of said pieces being positioned to conform to the contour of the surface of the work, said pole pieces being temporarily held in spaced apart relation, and applying a nonmagnetic binding material about these pieces to permanently bind them in fixed relation to each other.

3. An improved process of constructinga jig or fixture for electric chucks which con-V sists in placing extension pole pieces in a mold spaced to register with the pole pieces in the chuck, the work being used'as a pattern and the ends of said pieces being brought into contact therewith in setting, said pieces being temporarily supported in proper spaced apart relation, and applying a fluid binder which subsequently solidifies and hardens to support and retain said pieces in permanent relative position, thus producing a holding face conforming to the contour of the work, and subsequently surpieces being positioned to contact with and i conformed to the contour of that surface of the work to be held, said pole pieces being cast in a unit and supported in spaced apart relation by a tying member,and depositing a non-magnetic binding material around the pole pieces to retain them in permanent relation to each other thus producing a holding face conforming to the contour of the work and subsequently surfacing that portion adapted to engage the chuck.

In testimony whereof I aflix my signature in presence of two witnesses.

BENJAMIN M. WALPOLE.

WVitnesses:

HOWARD E. BARLOW, A. F. MAOREADY.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. G. 

